Lighting control systems are known wherein groups of lights within a room can be individually dimmed by different relative amounts and, upon the pressing of an appropriate switch, one of a plurality of dimming scenes which is preset can be automatically selected. For example, U.S. Pat. Nos. 4,575,660 and 4,727,296 disclose a lighting control system wherein a wall mounted control panel contains four pushbuttons for selecting one of the scenes, and four groups of linear potentiometers. Each group of potentiometers corresponds to one of the scenes that can be selected by the pushbuttons, and each of the linear potentiometers within each group corresponds to a lighting zone. For a particular scene, the lighting intensity for each zone is preset by adjusting the linear potentiometers in the group corresponding to that scene. A commercial embodiment of such a lighting control system has been manufactured and sold by Lutron Electronics Company, the assignee of the instant application, under the trademark AURORA.RTM.. In the system described in the '296 and '660 patents, and in the AURORA.RTM. commercial embodiment thereof, the control panel is located at a convenient location on a wall, but the actual power control electronics are remote from the control panel. Thus, in these systems, it is necessary to run wiring from the lighting zones to the power control electronics, and also from the control electronics to the control panel. Moreover, the number of zones that can be controlled by such systems is limited to the number of linear potentiometers that are provided, and it is not possible to easily expand an existing system to control additional zones.
The assignee of the instant application also manufactures and sells another wall mountable lighting control system under the trademark GRAFIK Eye.RTM.. The GRAFIK Eye.RTM. system is similar to the AURORA.RTM. system, but the power control electronics are integral with the control panel. However, the GRAFIK.RTM. Eye system suffers from the other disadvantages of the AURORA.RTM. system.
Another wall mounted control system is described in U.S. Pat. No. 4,733,138. A commercial embodiment of the system described in the '138 patent is manufactured and sold by Lightolier.RTM. Controls under the name SCENIST. These wall mounted control systems are microprocessor based and are user programmable via a display and control panel to define the desired scenes and desired intensity settings of the zones in each scene. The power control electronics for controlling the power delivered to the loads are integral with the control panel; that is, the power control electronics are not remote from the control panel. However, the number of zones that can be controlled is fixed and, like the systems described above, it is not possible to easily expand the number of zones that can be controlled by an existing system. While the systems are programmable, programming is complicated and requires the use of a "learn" button to initially program the system, as well as to implement any subsequent program changes. Programming these systems is confusing at best.
Another system manufactured by Lightolier.RTM. Controls is sold under the name COMPLI ENVIRONMENTAL CONTROL SYSTEMS. However, this system suffers from the same disadvantages as the system of the '138 patent and the SCENIST system.
The CENTAURI lighting system manufactured by Thyrocon and the SCENARIO manufactured by Lite Touch are other examples of wall mounted lighting control systems wherein different lighting scenes may be selected by the touch of a button. The power control electronics in these systems is integral with the control panel, but, as in the case of the other systems described above, the number of zones that can be controlled is fixed, and it is not possible to easily expand the number of zones that may be controlled by an existing system.
Another drawback of the systems described above is that they are limited in the types of loads that they are capable of controlling. In particular, these systems are specifically designed for controlling incandescent lighting, and in some cases, fluorescent lighting connected to magnetic dimming ballasts, but not other types of loads, such as motor driven loads or other inductive or capacitive loads. Another drawback is that at least some of these systems require connection to a neutral wire via a three wire hookup, and therefore are not adapted for retrofit installation where a neutral wire is not available and only a two-wire hookup can be effected. Still another drawback is that in at least some of these systems the number of available scenes is fixed to the number of pushbuttons on the control panel, and the number of scenes cannot be expanded.
It is therefore desirable to provide a wall mountable control system that is easy to program and is modular so that any number of lighting zones may be accommodated. It is also desirable that such system be expandable so that additional lighting zones may be added, if desired, at a later time. It is also desirable that the power control electronics be integral with the control panel, but that the system have the capability of communicating with a remote "power booster", or other existing lighting control system, if it is desired to control heavy loads, e.g., those having a current draw requirement in excess of 16A. The present invention achieves these and other goals.